Prognostic role of programmed cell death ligand-1 expression in head and neck cancer treated with programmed cell death protein-1/programmed cell death ligand-1 inhibitors: A meta-analysis based on clinical trials

Purpose: The purpose of our meta-analysis is to clarify whether the biomarker of programmed cell death ligand-1 (PD-L1) could predict the treatment efficacy and prognosis of programmed cell death protein-1 (PD-1)/PD-L1 immune-checkpoint inhibitors (ICIs) in head and neck cancer (HNC) patients. Materials and Methods: We performed the article search in four main online databases. The search deadline was September 8, 2020. To elucidate whether a positive or negative PD-L1 expression correlates with different efficacy and prognosis of PD-1/PD-L1-related therapy in HNC, the relative risk (RR) and 95% confidence interval (95% CI) were pooled. Our meta-analysis assigned the overall survival (OS) at 6 and 12 months and the objective response rate (ORR) for the primary end points. Results: The present meta-analysis included 11 relevant studies, which have 1663 HNC cases who received the treatment of PD-1/PD-L1 ICIs. The pooled results revealed that the high or positive expression of PD-L1 predicted better 6- and 12-month OS in head and neck squamous cell carcinoma (HNSCC) (RR 1.30, 95% CI: 1.02-1.65, P = 0.03; and RR 1.31, 95% CI: 1.05-1.62, P = 0.01). PD-L1 expressors were also relevant with higher ORR in HNC patients who had treatment of PD-1/PD-L1 inhibitors compared to PD-L1 nonexpressors (RR 1.84, 95% CI: 1.41-2.41, P < 0.00001). Conclusions: In summary, PD-L1-positive HNSCC patients portend favorable OS at 6 and 12 months from PD-1/PD-L1 ICIs. Increased ORR also favored to appear in PD-L1 expressors of HNC or recurrent/metastatic HNSCC who received PD-1/PD-L1 ICIs. Therefore, PD-L1 proved to be an appropriate biomarker to predict the clinical efficacy and prognosis of PD-1/PD-L1 ICIs in HNC.